I always felt like they intended for Guinan to be mysterious and wise (hence her interaction with Q in "Q Who"). Her hundreds-of-years lifespan and how she refers to her relationship with Picard solidifies this.
Unfortunately, I kind of think they ruined her species when they brought out Mazur in that one DS9 episode. He certainly didn't have any special powers- unless extra-strong sleaziness counts as a power.
Having the only OTHER El-Aurian we see be Soran didn't help matters much.